//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17

// <span>

// template<class ElementType, size_t Extent = dynamic_extent>
// class span {
// public:
//  // constants and types
//  using element_type           = ElementType;
//  using value_type             = remove_cv_t<ElementType>;
//  using size_type              = size_t;
//  using difference_type        = ptrdiff_t;
//  using pointer                = element_type *;
//  using reference              = element_type &;
//  using const_pointer          = const element_type *;
//  using const_reference        = const element_type &;
//  using iterator               = implementation-defined;
//  using const_iterator         = implementation-defined;
//  using reverse_iterator       = std::reverse_iterator<iterator>;
//  using const_reverse_iterator = std::reverse_iterator<const_iterator>;
//
//  static constexpr size_type extent = Extent;
//

#include <span>
#include <cassert>
#include <iterator>
#include <string>

#include "test_macros.h"

template <typename S, typename Iter>
void testIterator() {
  typedef std::iterator_traits<Iter> ItT;

  ASSERT_SAME_TYPE(typename ItT::iterator_category, std::random_access_iterator_tag);
  ASSERT_SAME_TYPE(typename ItT::value_type, typename S::value_type);
  ASSERT_SAME_TYPE(typename ItT::reference, typename S::reference);
  ASSERT_SAME_TYPE(typename ItT::pointer, typename S::pointer);
  ASSERT_SAME_TYPE(typename ItT::difference_type, typename S::difference_type);
}

template <typename S, typename ElementType, std::size_t Size>
void testSpan() {
  ASSERT_SAME_TYPE(typename S::element_type, ElementType);
  ASSERT_SAME_TYPE(typename S::value_type, std::remove_cv_t<ElementType>);
  ASSERT_SAME_TYPE(typename S::size_type, std::size_t);
  ASSERT_SAME_TYPE(typename S::difference_type, std::ptrdiff_t);
  ASSERT_SAME_TYPE(typename S::pointer, ElementType*);
  ASSERT_SAME_TYPE(typename S::const_pointer, const ElementType*);
  ASSERT_SAME_TYPE(typename S::reference, ElementType&);
  ASSERT_SAME_TYPE(typename S::const_reference, const ElementType&);

  static_assert(S::extent == Size); // check that it exists

  testIterator<S, typename S::iterator>();
  testIterator<S, typename S::reverse_iterator>();
}

template <typename T>
void test() {
  testSpan<std::span< T>, T, std::dynamic_extent>();
  testSpan<std::span<const T>, const T, std::dynamic_extent>();
  testSpan<std::span< volatile T>, volatile T, std::dynamic_extent>();
  testSpan<std::span<const volatile T>, const volatile T, std::dynamic_extent>();

  testSpan<std::span< T, 5>, T, 5>();
  testSpan<std::span<const T, 5>, const T, 5>();
  testSpan<std::span< volatile T, 5>, volatile T, 5>();
  testSpan<std::span<const volatile T, 5>, const volatile T, 5>();
}

struct A {};

int main(int, char**) {
  test<int>();
  test<long>();
  test<double>();
  test<std::string>();
  test<A>();

  return 0;
}
